The present invention relates generally to the field of manufacturing electronic devices. In particular, the present invention relates to the field of electronic devices containing low dielectric constant materials or ferroelectric polymers.
As electronic devices become smaller, there is a continuing desire in the electronics industry to increase the circuit density in electronic components, e.g., integrated circuits, circuit boards, multichip modules, chip test devices, and the like without degrading electrical performance, e.g., crosstalk or capacitive coupling, and also to increase the speed of signal propagation in these components. One method of accomplishing these goals is to reduce the dielectric constant of the interlayer, or intermetal, insulating material used in the components.
One method for reducing the dielectric constant of interlayer insulating material is to use certain organic materials as the insulating material. Another method is to incorporate within the insulating film very small, uniformly dispersed pores or voids, particularly within inorganic dielectric materials. Such porous dielectric materials have a reduced, and possibly substantially reduced, dielectric constant as compared to the same dielectric materials without the presence of pores.
A variety of organic and inorganic dielectric materials are known in the art in the manufacture of electronic devices, particularly integrated circuits. Suitable organic dielectric materials include thermosets such as polyimides, polyarylene ethers, polyarylenes, polycyanurates, polybenzazoles, benzocyclobutenes and the like. Suitable inorganic dielectric materials include silicon dioxide and organo polysilicas, among others.
In general, porous dielectric materials are prepared by first incorporating a removable porogen into a dielectric material, disposing the dielectric material containing the removable porogen onto a substrate, curing the dielectric material and then removing the polymer to form a porous dielectric material. For example, U.S. Pat. No. 6,271,273 (You et al.) discloses a process for forming an integrated circuit device containing porous organo polysilica dielectric material. U.S. Pat. No. 6,420,441 (Allen et al.) discloses a process for forming an integrated circuit containing porous organic or inorganic dielectric material.
Patterns are then typically etched in the porous or other low-dielectric constant (“low-k”) dielectric material by applying a photoresist, optionally in conjunction with an antireflective coating, to the low-k dielectric material, and imaging the resist followed by etching, such as reactive-ion etching (“RIE”). Following such patterning, the photoresist and any optional antireflective coating is then removed. The photoresists and optional antireflective coatings used in such process typically are cross-linked polymeric coatings.
When etched, such as with RIE, such cross-linked polymeric coatings become difficult to remove. One reason for such difficulty in removing these post-etch polymeric coatings is the formation of organometallic species on the exposed portions of the photoresist and antireflective coatings and on the sidewalls of the features etched into the dielectric material. Very strong polymer removers, such as fluoride-containing removers, must typically be used to completely remove such post-etch photoresist and antireflective coating polymers. Such removers may cause problems. For example, such removers may damage the fragile low-k dielectric material or ferroelectric polymer layers. The remover, such as fluoride ion, may absorb into such low-k dielectric material or ferroelectric polymer layer and seep out of such layer at a subsequent time, such as during subsequent processing steps or even during use of the integrated circuit, which may cause shorts or other problems in the device. Milder methods of removing such post-etch polymeric coatings are needed to prevent such problems.